JP2016540893A - Precipitation of copper-tin and copper-tin-zinc alloys from electrolytes - Google Patents

Abstract

The invention relates to a cyanide-free electrolyte comprising phosphoric acid and an aliphatic or aromatic thio compound and to a process for the electrolytic deposition of alloys containing elemental copper, tin and optionally zinc. is there. In these electrolytes and processes, the electrolyte used includes stannate ions, copper ions, and optionally zinc (II) ions, and aliphatic and / or aromatic thio compounds. The electrolyte may optionally contain additional carboxylic acids, wetting agents, and / or brighteners. The present invention further provides a process for electrolytically depositing an alloy of copper, tin, and optionally zinc on consumer goods and decorative articles using the electrolyte of the present invention.

Description

  The invention relates to a cyanide-free electrolyte comprising phosphoric acid and an aliphatic or aromatic thio compound and to a process for the electrolytic deposition of alloys containing elemental copper, tin and optionally zinc. is there. In these electrolytes and processes, the electrolyte used includes stannate ions, copper ions, and optionally zinc (II) ions, and aliphatic and / or aromatic thio compounds.

  It is well known to electrolytically deposit brass (copper-zinc alloy) and bronze (copper-tin alloy) on consumer goods and decorative items. These alloys are used inter alia as an alternative to nickel-containing finishing layers and are applied to suitable substrates, for example, by electrochemical drum coating or rack coating processes.

  In the manufacture of brass and bronze layers in the electronics industry, the solder properties of the finished layer and, in some cases, mechanical adhesion are important performances. In this field, the appearance of these layers is generally not important compared to the function in use. In contrast, when producing a brass or bronze layer on a consumer product, the decorative effect and durability of the layer with the least changeable appearance is an important required parameter.

  Conventionally known methods for the production of brass and bronze layers differ in the composition of the electrolyte in various electrochemical processes, as well as conventional methods that use cyanide and therefore use highly toxic alkaline baths. One of the two main process groups that are usually classified, one that uses an organic sulfonic acid electrolyte and the other that uses a diphosphate tank, is known. Diphosphate is also called pyrophosphate. Both processes have specific disadvantages, which significantly impede practical convenience. Thus, in any electrolytic system, divalent tin is added to oxidize to inactive tin (IV) during tank operation, but this significantly limits the life of the electrolyte. ing. In the case of the group of organic sulfonic acid electrolytes, further restrictions arise. They operate in a strongly acidic pH range and are therefore not suitable for special use, for example when coating pressure cast zinc.

  EP 2 032 743 (B1) describes an electrolyte for producing a copper-tin-zinc alloy layer for photovoltaic cells. This electrolyte is a phosphate / pyrophosphate system, in contrast to a conventional system that uses tin as stannic acid in a tetravalent state and does not use any conventional cyanide. From this electrolyte, a matte (matte) copper-tin-zinc layer can be deposited in a very narrow current density region. This type of electrolyte in the form described is not suitable for the production of decorative bronze layers by drum or rack plating.

  EP 1 961 840 (A1) discloses non-toxic electrolytes for the deposition of decorative bronze alloy layers. This electrolyte contains the precipitated metal in the form of a water-soluble salt and contains one or more phosphonic acid derivatives as a complexing agent, but does not contain cyanide, thiourea derivatives, and thio derivatives. It is. This electrolyte contains copper and tin, or a metal for depositing copper, tin and zinc. In this case, tin may be used as a divalent or tetravalent tin salt. Tin acid is not disclosed. In European Patent Application Publication No. 1961840 (A1), the bronze layer electrochemically deposited from the thiol-added tank has an appearance covered with spots or mats, and therefore, It is taught that it is not suitable for decorative coating.

  In WO 2013/093212 (A1), a process for the electrochemical deposition of a cyanide-free electrolyte containing pyrophosphoric acid and a ternary alloy of copper, tin and zinc is disclosed. In this case, in addition to zinc (II) ions and copper (II) ions, stannate ions are present in the electrolyte. When this electrolyte is used, a uniform white coating cannot be obtained in a wide current density range, so that it is not suitable for coating decorative articles.

  In WO 2013/092314 (A1), a process for electrolytic deposition of a ternary alloy of copper, tin and zinc and an electrolyte free of cyanide, free of pyrophosphoric acid and free of phosphonic acid It is disclosed. In this case, in addition to zinc (II) ions and copper (II) ions, stannate ions are present in the electrolyte. As in the case of the electrolyte disclosed in International Publication No. 2013/09312 (A1), when this electrolyte is used, a uniform white coating cannot be obtained in a wide current density range. It is not suitable for coating.

  In EP 2 071 057 (A2), compounds for electrolytic deposition of white bronze are disclosed. It contains tin, copper, and zinc ions and contains at least one mercaptan selected from the group consisting of mercaptotriazole and mercaptotetrazole. In the composition according to the invention, copper may be present in the form of copper (I) and copper (II) salts. The disclosed tin compounds are tin (II) salts. This compound does not contain any phosphate, pyrophosphate, or phosphonate. In all examples, bronze is precipitated at a pH value of 3 or less.

  In EP 1 001 054 (A2), an electrochemical cell for the deposition of tin-copper alloys is disclosed. This tank contains water-soluble tin (II) or tin (IV) salts, water-soluble copper (I) or copper (II) salts, organic or inorganic acids, or water-soluble salts thereof, and thioamide and thio At least one compound selected from the group consisting of compounds. When sodium tin (IV) is used, copper (I) cyanide is also used at the same time. Therefore, the electrolyte contains cyanide. The thio compound functions as a tank stabilizer or complexing agent. The inorganic acid or salt thereof may be phosphoric acid, condensed phosphoric acid, ie polyphosphoric acid, and phosphonic acid. The electrochemical cell according to EP 1 001 054 (A2) does not contain any zinc compounds. When using the electrochemical tank according to EP 1 0010 54 (A2), the appearance of the tin-copper alloy is white, depending on the copper content, the presence or absence of brighteners, and the water-soluble salt of the selected metal. It can be changed from grayish white, glossy to matte.

  WO 2010/003621 (A1) discloses an electrolytic cell for depositing decorative bronze. The electrolytic cell contains copper, tin, and optionally zinc, and further contains one or more phosphonic acid derivatives, disulfides, and carbonates or bicarbonates. In this case, tin is present as a tin (II) salt.

  It is an object of the present invention to deposit a cyanide-free electrolyte and corresponding white copper-tin alloy and white copper-tin-zinc alloy capable of depositing a uniform color coating on a decorative article over a wide current density range. Is to provide a process. This precipitation must be able to be performed optimally with favorable stoichiometry. The electrolyte must have a very simple composition. Furthermore, the process and electrolyte of the present invention must be superior from prior art processes and electrolytes in terms of environmental and economic aspects.

  These objects, and further objects apparent to the person skilled in the art from the prior art, can be realized by an electrolyte having the features of claim 1 and the corresponding process claimed in claim 10. Preferred embodiments of each invention are set out in the dependent claims of these claims.

The object of providing an electrolyte for the deposition of white copper-tin alloys and white copper-tin-zinc alloys is achieved by an aqueous electrolyte free of cyanide for the electrolytic deposition of copper, tin and optionally zinc alloys. This electrolyte is
Comprising at least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof;
And at least one compound selected from the group consisting of aliphatic and aromatic thio compounds,
Here, the deposited copper metal, and optionally zinc, is in dissolved form, tin is present as dissolved tin (IV) salt,
And the pH of the aqueous electrolyte which does not contain the said cyanide is 9 or more, and is an aqueous electrolyte.

In the electrolyte, at least one salt selected from the group consisting of phosphate, phosphonate, polyphosphate, diphosphate, and a mixture thereof is present in excess of copper and tin ions, and at the same time Advantageous copper-tin and copper-tin-zinc alloy compositions are disclosed herein when the copper and tin ions are set to a certain ratio and at the same time tin is present as a dissolved tin (IV) salt. It is known that it can be obtained from the electrolyte described in the book. In order to be able to precipitate a ternary alloy, both zinc and copper are present in a co-dissolved state when the electrolyte additionally contains zinc. The electrolyte additionally contains an aliphatic or aromatic thio compound that complexes the dissolved copper salt. The pH of the aqueous electrolyte of the present invention is 9 or more, and thus is alkaline. By using aliphatic and aromatic thio compounds in phosphoric acid and tin (IV) based copper-tin alloy electrolytes optionally containing zinc, copper is complexed and at the same time co-depositing of tin and optionally zinc Can be promoted in a current density range of 0.1 to 100 A / dm ^2, preferably 0.3 to 1.0 A / dm ² . This makes the usable current density range considerably wider than known electrolytes. When using the electrolyte of the present invention, uniform white coatings of copper-tin and copper-tin-zinc bronze are deposited over a wide range of applications.

  "Uniform" here means that the coating has a homogeneous appearance, i.e. it has the same color and properties of the same layer in terms of gloss, hardness and corrosion resistance. To do.

Using the electrolyte composition of the present invention, uniform white coatings of copper-tin bronze and copper-tin-zinc bronze can be deposited. The white color can be defined more accurately by measuring L ^* a ^* b ^* color.

Electrolytes based on stannic acid are known as prior art in the deposition of copper-tin and copper-tin-zinc alloys and are described, for example, at the beginning of EP 1 001 054 (A2). There, however, stannic acid is always used in combination with copper cyanide. In the cyanide complex, copper is essentially present as copper (I) cyanide, ie [Cu (CN) ₂ ] ⁻ . The deposition of a copper-tin layer from an electrolyte containing stannic acid and copper (I) cyanide is carried out at a pH value in the range of 12 to 13 in EP 1 001 054 (A2), The bronze layer was uneven in structure and color. In addition, burnt precipitates were observed in this bronze layer. Alkaline baths containing stannic acid and copper (I) cyanide are also inferior in bath stability.

  Using a combination of tin (II) salt and copper (I) cyanide instead of stannic acid and copper (I) cyanide does not result in a uniform copper-tin layer as well. II) is at least partially oxidized to tin (IV) in the presence of copper (I) cyanide, so that the above disadvantageous situation of the bath containing stannic acid and copper (I) cyanide occurs again Because.

  In the prior art, phosphates and pyrophosphates are used for the stabilization of copper-tin and copper-tin-zinc electrolytes. This is described at the beginning of, for example, International Publication Nos. 2013/09312 (A1) and 2013/092314 (A1). However, when these pyrophosphates or phosphates and stannic acid-based electrolytes containing no cyanide are used, a uniform white coating cannot be obtained over a wide current density range. In the case of the electrolyte disclosed there, the alloy composition is highly dependent on the current density used. In a relatively low current density range, a red coating is obtained with a high copper ratio and a low zinc ratio, while in a high current density range, the zinc ratio is significantly higher, but the coating is matt gray. is there. These electrolytes are therefore unsuitable for decorative coatings. In the high pH range, i.e., especially at pH values above 9 and including cyanide, the tin (IV) salt is stable and copper and tin can be deposited together in the form of a uniform white coating There is no known electrolyte.

  The aqueous electrolyte of the present invention and the deposition process of copper-tin and copper-tin-zinc alloy will be described below. The present invention encompasses all embodiments shown below, individually and in any combination.

  Copper may be added to the electrolyte in the form of a monovalent or divalent copper salt, or a mixture thereof. All optionally used zinc is present in the electrolyte in the form of divalent ions. Under the reaction conditions according to the invention, copper and any zinc are precipitated from their water-soluble compounds. Suitable copper and optional zinc water soluble compounds are pyrophosphate, carbonate, bicarbonate, sulfite, sulfate, phosphate, nitrite, nitrate, halide, hydroxide, hydroxide , Oxides, and mixtures thereof. The halide may be fluoride, chloride, bromide, or iodide. Copper, zinc carbonates, bicarbonates, sulfates, or pyrophosphates are preferred. In particular, copper and zinc sulfates are preferred. For the purposes of the present invention, the term “water-soluble” refers to copper and zinc salts having a solubility in water at 25 ° C. of at least 0.1 g / L.

  In an advantageous embodiment, copper is added to the electrolyte in the form of a copper (I) salt.

  In an advantageous embodiment, copper is added to the electrolyte in the form of a copper (II) salt.

Tin is added to the electrolyte of the present invention in the form of a tin (IV) salt, ie, a tetravalent form. Suitable tin (IV) salts are SnO ₂ , Sn (OH) ₄ , SnCl ₄ , SnBr ₄ , SnI ₄ , Sn (SO ₄ ) ₂ , Sn (NO ₃ ) ₄ , SnS ₂ , Na ₂ SnO ₃ , K ₂ SnO ₃ , K ₂ SnO ₇ C ₂ . In an advantageous embodiment, the tin (IV) salt is a stannate. A preferred stannate is sodium stannate Na ₂ SnO ₃ or potassium stannate K ₂ SnO ₃ . In a particularly advantageous embodiment, the tin (IV) salt is sodium stannate. In a further particularly advantageous embodiment, the tin (IV) salt is potassium stannate.

  The copper, tin, and optionally zinc salts present in the electrolyte of the present invention are collectively referred to herein as the “bronze forming salts”.

  The electrolyte of the present invention further comprises at least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures of these salts.

Suitable phosphates are, for example, disodium hydrogen phosphate and dipotassium hydrogen phosphate. Those skilled in the art will know that tribasic phosphoric acid dissociates over three stages and that both dihydrogen phosphate and hydrogen phosphate are amphoteric. It is known that the ratio of phosphate ion (PO ₄ ³⁻ ), hydrogen phosphate ion (HPO ₄ ²⁻ ) and dihydrogen phosphate ion (H ₂ PO ₄ ⁻ ) in the solution depends on the pH of the solution. It has been. Therefore, for the purposes of the present invention, phosphate ions, hydrogen phosphate ions, and dihydrogen phosphate ions are collectively referred to as “phosphate ions”. Similarly, tribasic phosphonic acids dissociate over three stages, and both dihydrogen phosphonate and hydrogen phosphonate are amphoteric. The salts of phosphonic acid are collectively referred to as “phosphonates”. Those skilled in the art know that both diphosphate and polyphosphate are also polybasic and the ratio of the respective anions of these acids depends on the pH of the solution as in the case of phosphoric and phosphonic acids. Will. For the purposes of the present invention, independent of the number of hydrogen atoms replaced by ammonium, lithium, sodium, or potassium cations in the diphosphate or polyphosphate hydrogen, these ammonium salts, lithium salts, sodium salts, And potassium salts can be used. The compounds of the group consisting of phosphates, phosphonates, polyphosphates, and diphosphates used in the electrolyte of the present invention are phosphoric acid, phosphonic acid, polyphosphoric acid, and diphosphoric acid salts. The salts here are advantageously the ammonium, lithium, sodium or potassium salts of these acids. In the case of polybasic acids in which one or more hydrogens are replaced by ammonium, lithium, sodium, or potassium cations, these cations may be the same or different.

  A “mixture” of phosphate, phosphonate, polyphosphate, and diphosphate includes at least two phosphates, at least two phosphonates, at least two polyphosphates, or at least two diphosphates. It may be a mixture of acid salts. Alternatively, these mixtures may be a mixture of at least two compounds of different groups of salts containing phosphorus and oxygen. Thus, for example, phosphates and phosphonates or two phosphates, and one diphosphate phosphate, phosphonate polyphosphate, and diphosphate are for purposes of the present invention. There are four groups of salts containing phosphorus and oxygen used in

  As described above, phosphate, phosphonate, polyphosphate, and diphosphate are present in excess of copper or tin ions in the electrolyte. Here, “in excess” means that the total number of moles of phosphate, phosphonate, polyphosphate, and diphosphate is larger than the total number of moles of copper and tin ions.

  In an advantageous embodiment, the total concentration in the electrolyte of at least one salt of the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof is between 0.05 mol / L and 5 0.0 mol / L.

  In a particularly advantageous embodiment of the invention, at least one salt of the group consisting of phosphates, phosphonates, polyphosphates and diphosphates in the cyanide-free aqueous electrolyte of the invention is It is hydrogen phosphate. Particularly preferred hydrogen phosphates are sodium hydrogen phosphate and dipotassium hydrogen phosphate. In an advantageous embodiment, the electrolyte comprises 20 to 150 g / L of dipotassium hydrogen phosphate.

  In a further advantageous embodiment, the electrolyte comprises 20 to 150 g / L of disodium hydrogen phosphate.

  Suitable pyrophosphates are, for example, sodium pyrophosphate, potassium pyrophosphate, or mixtures thereof. In an advantageous embodiment, the electrolyte comprises 5-40 g / L of potassium pyrophosphate. In a further advantageous embodiment, the electrolyte comprises 5-40 g / L of sodium pyrophosphate.

  In a further advantageous embodiment, the electrolyte is in the form of disodium hydrogen phosphate and / or dipotassium hydrogen phosphate, 20 to 150 g / L of hydrogen phosphate, preferably 90 g / L of hydrogen phosphate. Salts and 5 to 40 g / L pyrophosphate in the form of sodium pyrophosphate and / or potassium pyrophosphate.

  The electrolyte of the present invention additionally contains at least one compound selected from the group consisting of aliphatic and aromatic thio compounds. In an advantageous embodiment, at least one compound selected from the group consisting of aliphatic and aromatic thio compounds is present in the electrolyte at a concentration of 0.02 to 10 g / L.

Here, "at least one compound selected from the group consisting of aliphatic and aromatic thio compounds" means that the electrolyte of the present invention is
Exactly one aliphatic thio compound, or exactly one aromatic thio compound, or at least two thio compounds that are all aliphatic, or at least two thio compounds that are all aromatic, or -Means comprising at least one aliphatic thio compound and at least one aromatic thio compound;

  Suitable aliphatic thio compounds include, but are not limited to, aliphatic carboxylic acids and sulfonic acids containing thio groups. Suitable aromatic thio compounds include, but are not limited to, pyridine, pyrimidine, pyrazine, and hydantoin derivatives containing a thio group. In an advantageous embodiment, the thio compound is 2-mercaptopropionic acid, mercaptosuccinic acid, 2-thiopropanedicarboxylic acid, sodium 3-mercapto-1-propanesulfonate, 2-mercaptonicotinic acid, 2-thiouracil, 4 , 6-dihydroxy-2-mercaptopyrimidine, 2-mercaptopyrimidine, 2-thiocytosine, 6-mercaptopyrimidine-4-carboxylic acid, 2-mercaptopyrimidin-4-ol, 2-thiohydantoin, 5-sulfosalicylic acid Is done. The use of mercaptosuccinic acid and 4,6-dihydroxy-2-mercaptopyrimidine is particularly advantageous.

  In a further advantageous embodiment, 1 to 10 mL of 2-mercaptopropionic acid, 0.5 to 10 g of thiopropanedicarboxylic acid, 0.05 to 5 g of sodium 3-mercapto-propanesulfonate for each 1 L of electrolyte. The thio compound is selected from 0.05 to 5 g 2-mercaptonicotinic acid, 0.02 to 5 g 2-thiouracil, and 0.5 to 10 g 4,6-dihydroxy-2-mercaptopyrimidine.

  The pH of the aqueous electrolyte of the present invention is 9 or more. In a particularly advantageous embodiment, the electrolyte has a pH of 11 or higher.

  In particularly advantageous embodiments, the electrolyte of the present invention further comprises at least one of aliphatic, saturated or unsaturated dicarboxylic acids, or tricarboxylic acids, aromatic carboxylic acids, salts, and mixtures thereof. “At least one of carboxylic acid, salt, and mixture thereof” means that the following carboxylic acid and salt thereof may be used independently or in any combination. The aliphatic saturated dicarboxylic acid is advantageously selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, malic acid. The aliphatic unsaturated dicarboxylic acid is preferably selected from maleic acid and fumaric acid. A preferred tricarboxylic acid is citric acid. Suitable aromatic carboxylic acids are, for example, benzoic acid, benzene-1,3,5-tricarboxylic acid, and salicylic acid. The salts of carboxylic acids mentioned are preferably ammonium, lithium, sodium or potassium salts. In the case of a salt of a polybasic carboxylic acid, one or more or all of the hydrogen atoms of the carboxyl group may be substituted with ammonium, lithium, sodium, or potassium ions. In the case of polybasic carboxylic acids in which at least two carboxylic hydrogens are replaced by ammonium, lithium, sodium, or potassium ions, these ions may be the same or different. The total concentration of carboxylic acid or salt thereof is preferably 5 to 100 g / L of electrolyte.

  In an advantageous embodiment, the carboxylic acid is selected from oxalic acid, tartaric acid and citric acid, or the salt of the carboxylic acid is selected from oxalate, tartrate and citrate.

In a particularly advantageous embodiment, the carboxylic acid or salt thereof is oxalic acid or oxalate. The use of dipotassium oxalate (K ₂ C ₂ O ₄ ) is very particularly advantageous.

  In a further particularly advantageous embodiment, tartaric acid or a salt thereof, such as potassium sodium tartrate, is used.

  In a further particularly advantageous embodiment, citric acid or a citrate salt, such as potassium citrate, is used.

  In a further advantageous embodiment, the electrolyte according to the invention comprises at least one additional salt. The anions of these salts are sulfate ion, fluorine ion, chlorine ion, bromine ion, iodine ion, carbonate ion, formate ion, acetate ion, propionate ion, butyrate ion, valeric ion, nitrate ion, nitrite ion, sulfone. It is selected from the group consisting of acid ions, alkyl sulfonate ions, particularly methane sulfonate ions, amido sulfonate ions, sulfamate ions, aminocarboxylic acids and N-heterocyclic carboxylic acid anions. The cation of these salts is selected from ammonium, lithium, sodium, and potassium ions. In the case of polybasic acids, one or all hydrogen atoms are replaced by the mentioned cation. When two or more hydrogen atoms are replaced by the above cations, these cations may be the same or different. This at least one additional salt is hereinafter referred to as a “conductive salt”.

  In a further advantageous embodiment, the electrolyte according to the invention additionally comprises at least one brightener. The addition of brighteners to the electrolyte for deposition is known to those skilled in the art and can be used without going beyond the scope of protection of the claims. The brightener is preferably bis (3-sulfopropyl) disulfide disodium salt, 3-sulfopropyl O-ethyldithiocarbonate potassium salt, 1- (3-sulfopropyl) -pyridinium betaine, 1- (2-hydroxy -3-sulfopropyl) -pyridinium betaine, 3- (2-benzothiazole-2-mercapto) propanesulfonic acid sodium salt, S-isothiouronium 3-propanesulfonate, 3- (sulfopropyl) N, N-dimethyldithio Carbamate sodium salt, 1-benzyl-3-sodium carboxypyridinium chloride, 3-formyl-1- (3-sulfopropyl) pyridinium betaine, N- (3-sulfopropyl) saccharin sodium salt, saccharin sodium salt, carboxyethylisothiouro Umbetaine, cocoamido-propyldimethylammonium 2-hydroxypropanesulfobetaine, N- (3-cocoamidopropyl-N, N-dimethyl) -N- (3-sulfopropyl) ammonium betaine, 6-carboxy-2,4-dihydroxy It is selected from pyrimidine and 2-butenoic acid.

In a further advantageous embodiment, the electrolyte according to the invention additionally comprises at least one wetting agent. The addition of wetting agents to the electrolyte for bronze deposition is known to those skilled in the art and can be used without going beyond the scope of protection of the claims. The wetting agent is advantageously selected from:
A cationic amine polymer having a urea group,
- consists of morpholine, epichlorohydrin, and imidazole _monomers, cation having the general formula ^{_{(C 4 H 9 NO) x}} * (C 3 H 5 ClO) y * (C 3 H 4 N 2) z Sex polymer,
A cationic polymer composed of monomers of epichlorohydrin and imidazole and having the general formula of (C ₃ H ₅ ClO) _x ^* (C ₃ H ₄ N ₂ ) _y
-N-alkyl-N- (1-oxoalkyl) amino acids and derivatives and salts thereof and mixtures of these wetting agents.

  If a salt of an N-alkyl-N- (1-oxoalkyl) amino acid is used, it is preferably an ammonium, lithium, sodium or potassium salt.

  By using brighteners and wetting agents, the gloss of the layer can be set to all gradations from silk matte to high gloss.

A particularly advantageous embodiment of the invention is an electrolyte having the following composition:
General composition 1:
-Bronze forming salts,
-At least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof;
-At least one compound selected from the group consisting of aliphatic and aromatic thio compounds.

General composition 2:
-Bronze forming salts,
-At least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof;
-At least one compound selected from the group consisting of aliphatic and aromatic thio compounds,
At least one of aliphatic, saturated or unsaturated dicarboxylic acids, or tricarboxylic acids, aromatic carboxylic acids, salts, and mixtures thereof.

General composition 3:
-Bronze forming salts,
-At least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof;
-At least one compound selected from the group consisting of aliphatic and aromatic thio compounds,
At least one conductive salt;

General composition 4:
-Bronze forming salts,
-At least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof;
-At least one compound selected from the group consisting of aliphatic and aromatic thio compounds,
At least one of aliphatic, saturated or unsaturated dicarboxylic acids, or tricarboxylic acids, aromatic carboxylic acids, salts, and mixtures thereof;
At least one conductive salt;

  Further particularly advantageous are embodiments of the invention in which the electrolyte having the above general composition 1-4 comprises at least one brightener, at least one wetting agent, or at least one brightener and at least one wetting agent. . All particularly advantageous embodiments of the electrolyte of the present invention are aqueous, cyanide free and have a pH of 9 or higher.

  According to the present invention, metallic copper and optional zinc are present in the electrolyte in an ion-dissolved state, and tin is present as stannic acid or other tin (IV) salt. The ion concentration of copper is preferably 0.05 to 10 g / L, the ion concentration of tin as stannic acid is preferably 0.5 to 40 g / L, and the ion concentration of zinc is preferably 0. .1 to 10 g / L. The ion concentration of copper is 0.5 to 2.0 g / L of the electrolyte, the ion concentration of tin as stannic acid is 10 to 20 g / L of the electrolyte, and the ion concentration of zinc is 2.0 to 4.0 g / L. This is particularly advantageous. These indicated advantageous ion concentrations of copper, tin and optionally zinc apply to all of the preferred embodiments described above.

  The present invention likewise immerses the substrate to be coated as a cathode in the electrolyte of the present invention, and passes a current between the anode and the cathode to electrolytically deposit copper-tin and copper-tin-zinc alloy layers. A process is also provided. It goes without saying that the preferred embodiments in the electrolyte are equally preferred in the process.

  In the ternary alloy to be precipitated, the copper ratio is advantageously in the range of 20-80% by weight, the tin ratio in the range of 10-60% by weight and the zinc ratio in the range of 1-30% by weight. is there. Here, the sum of the proportions of all the metals involved in the alloy is 100% by weight in each case.

  In the case of a binary alloy, the copper ratio is in the range of 30 to 90% by weight and the tin ratio is in the range of 10 to 70% by weight. The sum of the proportions of all participating metals in the alloy is 100% by weight in each case.

  In an advantageous embodiment, the precipitated ternary alloy is in the alloy with a copper proportion of 50-60% by weight, a tin proportion of 35-45% by weight and a zinc proportion of 5-15% by weight. It is a white layer where the sum of the proportions of all metals involved is 100% by weight.

  In all embodiments described herein, the deposited alloy has a thickness of 0.4-5 μm, preferably 0.5-3 μm, particularly preferably 1-2 μm.

  Similarly, it is noted that the alloy composition can vary with temperature during electrolysis. Therefore, the electrolysis is performed in the range of 20-90 ° C, preferably in the range of 30-60 ° C, particularly preferably about 45 ° C.

  Similarly, the composition of a binary alloy of copper and tin, or a ternary alloy of copper, tin and zinc varies depending on the current density set during electrolysis. Advantageously, the current density is set in the range of 0.1 to 100 amperes per square decimeter. The current density is preferably 0.2 to 5.0 amperes per square decimeter, and particularly preferably 0.3 to 1 amperes per square decimeter.

  As the anode, any electrode that would be considered for this purpose by those skilled in the art can be used. It is preferred to use an insoluble anode (eg, a platinum-titanium anode or a mixed metal oxide anode). In this context, a soluble material comprising a material selected from the group consisting of electrolytic copper, phosphorus-containing copper, tin, tin-copper alloy, zinc-copper alloy, and zinc-tin-copper alloy, or combinations of these anodes An anode can be used as well.

  The electrolyte of the present invention and the process of the present invention can be used to electrolytically deposit copper, tin, and optionally zinc alloys into consumer goods and decorative articles.

Claims (16)

A cyanide-free aqueous electrolyte for electrolytic deposition of alloys of copper, tin, and optionally zinc,
Comprising at least one salt selected from the group consisting of phosphates, phosphonates, polyphosphates, diphosphates and mixtures thereof;
And at least one compound selected from the group consisting of aliphatic and aromatic thio compounds,
Here, the deposited copper metal, and optionally zinc, is in dissolved form, tin is present as dissolved tin (IV) salt,
And pH of the aqueous electrolyte which does not contain the said cyanide is 9 or more aqueous electrolyte.   The electrolyte of claim 1 further comprising at least one of an aliphatic, saturated or unsaturated dicarboxylic acid, or tricarboxylic acid, aromatic carboxylic acid, salt, and mixtures thereof. Anion is sulfate ion, fluorine ion, chlorine ion, bromine ion, iodine ion, carbonate ion, acetate ion, formate ion, propionate ion, butyrate ion, valerate ion, benzoate ion, nitrate ion, nitrite ion, sulfone Selected from the group consisting of acid ions, alkyl sulfonate ions, amido sulfonate ions, sulfamate ions, aminocarboxylic acids and N-heterocyclic carboxylic acid anions,
The electrolyte according to claim 1 or 2, wherein the cation further comprises at least one salt selected from ammonium ions, lithium ions, sodium ions, and potassium ions.   Bis (3-sulfopropyl) disulfide disodium salt, 3-sulfopropyl O-ethyldithiocarbonate potassium salt, 1- (3-sulfopropyl) -pyridinium betaine, 1- (2-hydroxy-3-sulfopropyl)- Pyridinium betaine, 3- (2-benzothiazole-2-mercapto) propanesulfonic acid sodium salt, S-isothiouronium 3-propanesulfonate, 3- (sulfopropyl) N, N-dimethyldithiocarbamate sodium salt, 1-benzyl -3-sodium carboxypyridinium chloride, 3-formyl-1- (3-sulfopropyl) pyridinium betaine, N- (3-sulfopropyl) saccharin sodium salt, saccharin sodium salt, carboxyethylisothiouronium betaine, Amido-propyldimethylammonium 2-hydroxypropanesulfobetaine, N- (3-cocoamidopropyl-N, N-dimethyl) -N- (3-sulfopropyl) ammonium betaine, 6-carboxy-2,4-dihydroxypyrimidine, The electrolyte according to any one of claims 1 to 3, further comprising at least one brightener selected from the group consisting of 2-butenoic acid. ○ Cationic amine polymer having a urea group,
○ morpholine, constructed from monomers of epichlorohydrin, and _imidazole, cation having a general formula of ^{_{(C 4 H 9 NO) x}} * (C 3 H 5 ClO) y * (C 3 H 4 N 2) z Sex polymer,
A cationic polymer composed of epichlorohydrin and imidazole monomers and having the general formula of (C ₃ H ₅ ClO) _x ^* (C ₃ H ₄ N ₂ ) _y ;
The composition further comprising at least one wetting agent selected from: N-alkyl-N- (1-oxoalkyl) amino acids and derivatives and salts thereof; and a mixture of these wetting agents. The electrolyte according to any one of the above.   The metal copper and any zinc to be deposited are in an ion-dissolved form, and the tin is present as a tin (IV) salt, where the copper ion concentration is 0.05 to 10 g / L of the electrolyte. The ion concentration of tin is in the range of 0.5 to 40 g / L of the electrolyte, and the ion concentration of zinc is in the range of 0.1 to 10 g / L of the electrolyte. The electrolyte according to claim 1.   The metal copper and any zinc compound precipitated, water-soluble under given conditions, is pyrophosphate, carbonate, bicarbonate, sulfite, sulfate, phosphate, nitrite, nitrate The electrolyte according to any one of claims 1 to 6, which is selected from the group consisting of: a halide, a hydroxide, a hydroxide oxide, an oxide, and a mixture thereof.   The electrolyte according to claim 1, wherein the dissolved tin (IV) salt is a stannate.   The thio compound is 2-mercaptopropionic acid, mercaptosuccinic acid, 2-thiopropanedicarboxylic acid, sodium 3-mercapto-1-propanesulfonate, 2-mercaptonicotinic acid, 2-thiouracil, 4,6-dihydroxy-2. -Mercaptopyrimidine, 2-mercaptopyrimidine, 2-thiocytosine, 6-mercaptopyrimidine-4-carboxylic acid, 2-mercaptopyrimidin-4-ol, 2-thiohydantoin, 5-sulfosalicylic acid. The electrolyte of any one of -8.   A process for electrolytic deposition of an alloy comprising elemental copper, tin, and optionally zinc, wherein the substrate coated with the electrolyte according to any one of claims 1-9 is a cathode. A process in which a current is passed between the anode and the cathode.   The ratio of copper in the alloy is in the range of 20 to 80 wt%, the ratio of tin is in the range of 10 to 60 wt%, the ratio of zinc is in the range of 1 to 30 wt%, The process according to claim 10, wherein the sum of the proportions of all metals involved in the alloy is 100% by weight.   The ratio of copper in the alloy is 50-60 wt%, the ratio of tin is 35-45 wt%, the ratio of zinc is 5-15 wt%, and the ratio of all the metals involved in the alloy The process according to claim 10, wherein the total is 100% by weight.   The ratio of copper in the alloy is in the range of 30 to 90% by weight, the ratio of tin is in the range of 10 to 70% by weight, and the sum of the ratios of all contained metals in the alloy is 100. The process of claim 10, wherein the process is% by weight.   The process according to any one of claims 10 to 13, wherein the electrolyte is maintained in the range of 20 to 90C.   15. The process according to any one of claims 10 to 14, wherein the current density is set in the range of 0.1 to 100 amperes per square decimeter.   An insoluble anode (eg, platinum-titanium anode or mixed metal oxide anode) or selected from the group consisting of electrolytic copper, phosphorus-containing copper, tin, tin-copper alloy, zinc-copper alloy, and zinc-tin-copper alloy 15. The process according to any one of claims 10 to 14, wherein a soluble anode comprising a material or a combination of these anodes is used.